636 



After this operation the entire dorsal portion of the isolated 

 derinatoma was found to have lost sensibility. To make the ventral 

 demarcation of the area that has been made insensible in this way 

 rightly understood, 1 may add the following: For a long time I had 

 been struck by the fact that after a carefully performed root-isolation, 

 the demarcation-lines of the isolated root-areas showed at a definite 

 point a distinct bent. The origin of this bent is, that at some 

 distance from the mid-dorsal line of the body, both the cranial 

 and the caudal demarcation lines of the root-area, change their 

 direction somewhat cranialward. In the cranial demarcationline this 

 bent is always found a little more dorsalward than in the caudal 

 demarcationline. Now it is remarkable, that the ventral limit of the 

 insensible zone, originated by the sectioning of the dorsal nerve- 

 branches, is invariably found to be a straight line, connecting the 

 cranial with the caudal limit just above this bent. This line therefore 

 goes in a cranio-caudal direction. At the same time however it 

 deviates slightly in a dorso-ventral direction. Consequently the 

 latero-ventral nerves supply within the root-area the innervation of 

 a zone extending to a point somewhat above the alleged bent in 

 its demarcation-lines. 



h. If the conduction is interrupted in the joint latero-ventral 

 branches, the entire ventral portion of the root-area becomes insensible. 



Fig. 4. The same as in Fig. 3, only for branches of the latero- 

 ventral trunk. (The isolated root-area is probably in the mainTh. 12. 

 Its closer definition was neglected in the necropy.) 



If we compare the demarcationline found in this waj', with that 

 found after interrupting the conduction in the dorsal branches, it 

 becomes evident that the ventral boundary of the dorsal area does 



